< cpp‎ | ranges‎ | take view‎ | sentinel
Ranges library
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(until C++23)(C++23)

friend constexpr bool

    operator==( const std::counted_iterator<ranges::iterator_t<Base>>& y,

                const /*sentinel*/& x );
(1) (since C++20)
template< bool OtherC = !Const >

    requires std::sentinel_for<ranges::sentinel_t<Base>,
                               ranges::iterator_t</*add-const-if*/<OtherC, V>>>
friend constexpr bool operator==( const std::counted_iterator<ranges::iterator_t<
                                      /*add-const-if*/<OtherC, V>>>& y,

                                  const /*sentinel*/& x );
(2) (since C++20)

Compares a take_view::/*sentinel*/ with a std::counted_iterator (typically obtained from a call to take_view::begin).

Returns true if y points past the Nth element (where N is the number passed to the constructor of take_view), or if end of underlying view is reached.

The exposition-only alias template /*add-const-if*/ is defined as
template<bool C, class T>
using /*add-const-if*/ = std::conditional_t<C, const T, T>;

These functions are not visible to ordinary unqualified or qualified lookup, and can only be found by argument-dependent lookup when std::ranges::take_view::sentinel<Const> is an associated class of the arguments.

The != operator is synthesized from operator==.


[edit] Parameters

y - std::counted_iterator to compare
x - sentinel to compare

[edit] Return value

y.count() == 0 || y.base() == x.end_, where end_ denotes the underlying sentinel.

[edit] Example

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 3449 C++20 comparison between the iterator and the sentinel of
differently const-qualified take_view was unsupported
made supported when possible